A common macro I use is:

/cast [target=focustarget,exists,nomod] spell
/cast [target=focustarget,exists,mod:shift] different spell

this gives me two spells for the cost of one UI button. I used to use bartender and addons like that but I've finally given up on constantly updating and configuring them, now I just use the default action bars and I have no problems...ever

and when I set my focus, I have found

/target main
/focus
/cleartarget

to work more reliably than /focus main

Since I've switched from hardware to software, I use keyclone's method of setting the focus at the same time I switch screens. The only complex macro I have is for follow. I use the the focusless, macroless method for follow. I have found it also more reliable than /follow focus.

Another thing to look out for is to make sure keybindings across all characters are exactly the same and use 'do no pass" feature of keyclone.